I would give them their space, make sure he has a good hiding place in viv. This will give him security, start out with a routine of feeding. 6 - 9 months would be round about the cutoff for feeding everyday, minimize feeding so he will eat when you feed him, what I did was have a secure spot for their feeding cup, put in same place same time everyday, at first put cup in viv. Then close the door & walk away, give space, then gradually over 1 - 2 months for me they got to know feeding time and would be anxious to eat and meet me at the door, then I would hand feed, by then my presence wasn't a threat, I'm now associated with something to eat or drink = trusted. Some chams will take longer to tame, consistency and routine will achieve trust, along with having good husbandry= correct temps, correct uv lighting proper viv size and plants to hide in and vines to crawl on